The invention relates to disc-type friction clutches and brakes and, more particularly, it relates to arrangements for adjusting the stroke of the actuating piston in such clutches and brakes.
The invention can be used to utmost effectiveness in both the existing forging machines and presses and those being built, since rapidity of engagement and disengagement of the clutches and brakes in such machines and presses is essential.
More often than not the existing arrangements for adjusting the stroke of a piston include washers.
Two commonly known types of such arrangements are available. The first type is one including two washers of which the first, acting as the piston-washer, has stepped radially through recesses. The other washer likewise has stepped recesses so that this washer can be centered relative to the piston-washer by engagement of the external surface of the piston-washer with the internal surface of the stepped recesses of the second washer. Adjustment of the piston stroke value is effected by rotating one of the washers relative to the other one, which has proved to be a time-consuming operation. The washers are retained in an adjusted position with aid of a locking device of which one part is located on the external surface of the cylinder receiving the piston-washer, and the other part is carried by the second washer. The incorporation of the locking device complicates the structure of the entire apparatus. Moreover, sophisticated machinery is to be used in the manufacture of washers with stepped recesses.
The other type of adjusting arrangements includes a washer with radial recesses of different depths, accomodated between a housing and a flange of a cylinder receiving a piston reciprocating therein, the housing and the cylinder being rigidly secured to each other, the stroke of the piston being limited by the washer (see, for example, Swiss Patent No. 376,728, Cl. 47 c; 9, issued in 1964). In this last-described type of the arrangement adjustment of the piston stroke is carried out, similarly to the first-described type of the arrangement, by rotating the cylinder flange about its own axis, which brings about considerable difficulties in cases where the brake or the clutch are of large dimensions. Furthermore, the rotation of these bulky parts is a time-consuming operation. Moreover, in the last-described apparatus of the prior art bushes and bolts are incorporated to secure the washer to the housing, which complicates the structure of the arrangement, as a whole, and hampers the operations of mounting and removing the washer when the friction linings of the brake or of the clutch become worn out.